Electrical power source



Nov. 10; 1970 c. J- CAMPAGNUOLO 3,539,840

' ELECTRICAL POWER SOURCE Filed Dec. 27. 1966 INVENTOR CARL. J. CAMPAGNUOLO #0 5* W WORNEYS United States Patent 3,539,840 ELECTRICAL POWER SOURCE Carl J. Campagnuolo, Chevy Chase, Md., assignor to the United States of America as represented by the Secretary of the Army FiledDec. 27, 1966, Ser. No. 605,108 Int. Cl. H02n 11/00 US. Cl. 310-2 3 Claims ABSTRACT OF THE DISCLOSURE Air is passed through the longer side of an L-shaped hollow tube. The air is discharged from the shorter side of the L-shaped hollow tube and passed parallel to an entrance port of a Helmholtz fluid resonator. One side of the Helmholtz resonator is defined by a diaphragm which has the same resonant frequency as the resonator itself. A connecting rod at one of its ends is joined to said diaphragm and at its other end to a soft iron reed which is surrounded by an electrical coil having two output wires. Surrounding the electrical coil is a permanent magnet. When the pressure of the air discharging from the shorter side of the hollow tube matches the resonant frequency of the Helmholtz resonator, resonance occurs, and the diaphragm is vigorously vibrated and, by the connecting rod, vigorously vibrates the soft iron reed between the poles of the permanent magnet. Since the electrical coil is inside the permanent magnet a voltage is induced across the two output wires of the electrical coil.

This invention relates to electrical generating means, and in particular, to a device that is capable of selectively transforming pressure energy of a certain magnitude into a small quantity of electrical energy.

Prior art devices to convert pressure energy into a low value electrical voltage have in the past been complex and expensive. A typical prior art device to convert a pressure energy signal into a low value electrical voltage was a small air turbine which rotated the armature of an electrical generator. While this device was successful in generating low value electrical voltages it was quite complex in design and tended to produce inconsistant voltages due to changes in the pressure of the working fluid.

It is therefore an object of this invention to provide improved means to convert pressure energy into a low value electrical voltage.

Another object of the present invention is to provide means to convert a pressure signal of a certain magnitude into an electrical voltage.

A further object of the present invention is to provide inexpensive and simple means to convert a pressure signal of a specified magnitude into a low value electrical voltage and to not utilize said pressure signal when the magnitude thereof is above or below said specified magnitude.

Briefly, in accordance with the present invention, air is passed parallel to the entrance port of a Helmholtz resonator. A connecting rod couples a diaphragm, which serves to define one end of the Helmholtz resonator, with a soft iron reed which is surrounded by an electrical coil having two output wires. A permanent magnet having an air gap surrounds the electrical coil. When the pressure of the air matches the resonant frequency of the resonator, resonance will occur, and the diaphragm will vigorously vibrate the soft iron reed by the connecting rod. The vibrating soft iron reed will change the flux in the air gap of the permanent magnet inducing a voltage across the electrical coil. If the pressure of the air passing parallel to the entrance port of the resonator is above or below the resonant value of the resonator there will not be a resonant condition in the resonator and the diaphragm will not vibrate and hence no voltage will be induced across the output wires of the electrical coil.

Other objects and aspects of the invention will be clear from the foregoing specification and drawing in which the figure is a schematic illustration of my invention.

Referring now to the figure an electrical generating means is shown including a hollow L-shaped tube 11. An entrance port 13 is at one end of the longer side of L-shaped tube 11 while a discharge port 15 is positioned at the end of a shorter side 14 of L-shaped hollow tube 11. Discharge port 15 is positioned to blow air parallel to an entrance port 16 of a Helmholtz resonator 120. Helmholtz resonator has a hollow cylindrical section 17 which communicates entrance port 16 with a conically shaped section 18. Integral with conically shaped section 18 of the Helmholtz resonator is a base portion 19 which consists of a cylindrical section having a constant cross sectional area. A diaphragm 20 having the same frequency as the Helmholtz resonator, is attached to end 27 of section 19 of the resonator. Attached, by conventional means, to the center portion of diaphragm 20 is a connecting rod 21. A soft iron reed 22 is joined to the opposite end of connecting rod 21 that is attached to diaphragm 20 and is inside an electrical coil 24 and positioned to pivot at end 48 within a permanent magnet 23 which surrounds electrical coil. Permanent magnet 23 has two pole pieces 40 and 42 of opposite polarity and air gaps 44 and 46'are formed between reed 22 and pole pieces 42 and 40. Output wires 25 and 26 are part of electrical coil 23 and extend through the top of permanent magnet 23.

In operation air having a velocity vector indicated by arrow 12 is passed through hollow tube 11 by entrance port 13 and discharged from discharge port 15 parallel to entrance port 16 of Helmholtz resonator 120. If the pressure of the air discharging from discharge port 15 matches the resonant frequency of Helmholtz resonator 120, resonance will occur with a resulting vigorous vibration of diaphragm 20. (A discussion of this phenomenon can be found in Fundamentals of Acoustics, by Kinzer and Frey, published by John Wiley and Sons, 1962). When diaphragm 20 vibrates, soft iron reed 22, by connecting rod 21, will vibrate between pole pieces 40 and 42 changing the magnetic reluctance in air gaps 44 and 46 inducing an electromotive force in coil 24 which can be utilized by output wires 25 and 26. If the pressure discharging from discharge port 15 is above or below the pressure needed to match the resonant frequency of Helmholtz resonator 120, resonance will not occur, and diaphragm 20 will not be vibrated with a resulting lack of movement of reed 22 and no voltage will be induced in coil 24.

From the foregoing it is apparent that I have provided novel means to utilize a pressure signal of a certain magnitude to generate an electromotive force. Since the frequency of resonator 120 is a function of the pressure passed parallel to its entrance port, and since only a pressure of a certain magnitude will be utilized by resonator 120, it can be seen that when resonance occurs it will produce vibrations of diaphragm 20 within a narrow frequency range. As reed 22 moves with diaphragm 20 it can be seen that the reed will change the magnetic flux in air gaps 44 and 46 at a constant rate and thus produce and electromotive force in coil 24 that will be of a relatively constant magnitude.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

I 1; "Apparatus for generating 511' elect roniotiile fr'c" from a pressure signal, comprising:

(a). a Helmholtz resonator utilizinga pressure. signal motion comprising an enclosed vo1ume having "a of a predetermined magnitude to produce-vibratory motion comprising an enclosed volume having a f diaphragm at one end thereof andan entrance port at the opposite endthereof; (b) means discharging a pressure s'ignalperpendicular to and across said entrance port; and (0) means coupled to said diaparagm for "translating said vibratory motion into electrical energy.

7 2. A device according to claim 1 wherein said means to pass said pressure signal across said entrance port tjoned adjacent said entrance port.

by an electrical coil anda p'ermanentmagnet.

' UNITED STATES PATEN s 2,539,535; 1/1951. Espenschied 310 8.1 X

. RICHARD A. FARIQEY, Prirnary E Xaminer L. RIBANDO, Assistant Examin'er I ueer. X11; f 322-.3 

